1. Field of the Invention
The present invention relates to a socket for electrical parts for detachably accommodating and holding an electrical part such as a semiconductor device (called as xe2x80x9cIC packagexe2x80x9d hereinlater), and more particularly, relates to a socket for electrical parts having improved contact pins to be contacted to or separated from terminals of the electrical part.
2. Related Art of the Invention
In a known art, an IC socket of the type mentioned above is preliminarily disposed on a printed circuit board and an IC package is then mounted to and accommodated in this IC socket to thereby establish an electrical connection between the IC package and the printed circuit board.
In such prior art as mentioned above, however, the IC packages includes an LGA (Land Grid Array) type of a structure in which a number of plate-shaped electrodes as terminals are disposed to a lower surface of a rectangular plate-shaped package body.
In this type of the IC package, under the accommodated state of the IC package in the IC socket, when a number of plate-shaped electrodes are contacted to contact portions formed to upper end portions of contact pins of the IC socket, the electrical connection between the respective plate-shaped electrodes of the IC package and the printed circuit board are established through the respective contact pins.
Such prior art structure will be explained hereunder with reference to FIGS. 12A and 12B, for example. That is, the contact pin 1 is composed of an upper contact portion 1a, a lower contact portion 1b and an intermediate elastic portion 1c as viewed in FIG. 12A or 12B. The upper contact portion contacts the plate shaped electrode of the IC package 2 when the contact pin 1 contacts the IC package 2, the lower contact portion 1b contacts the printed circuit board 3, and the elastic portion 1c has a circularly curved shape and the upper and lower contact portions 1a and 1b are connected through this elastic portion 1c. 
The upper and lower contact portions 1a and 1b are inserted into through holes 4a and 4b, respectively, formed to a socket body 4 of an IC socket so that the inserted tip end portions are contacted to the IC package 2 and the printed circuit board 3, respectively, and pressed and then deformed.
However, in the conventional structure such as mentioned above with reference to FIGS. 12A and 12B, the contact pin 1 is elastically deformed. That is, the upper contact portion 1a abuts against the plate-shaped electrode 2a of the IC package 2 and the lower contact portion 1b abuts against the printed circuit board 3, and in this state, these contact portions 1a and 2b are pressed in directions of arrows in FIG. 12A. Accordingly, the central arcuate elastic portion 1c is deformed and flexed as shown by an arrow in FIG. 12B. In this operation, the upper and lower contact portions 1a and 1b, which are perpendicularly aligned, are obliged to be inclined and contacted to (interfere with) peripheral edge portions of the through holes 4a and 4b of the socket body 4. In such state, smooth vertical motion of the contact portions 1a and 1b will not be expected, thus being inconvenient.
An object of the present invention is to substantially eliminate defects or drawbacks encountered in the prior art mentioned above and to provide a socket for electrical parts capable of preventing the contact pin from interfering with the socket body at the time of deformation thereof to carry out smooth motion of the contact pin.
This and other objects can be achieved according to the present invention by providing, in one aspect, a socket for an electrical part having a socket body to which a number of contact pins are arranged, in which the each of the contact pins has one end portion which electrically contacts a terminal of an electrical part and another one end portion which electrically contacts a printed circuit board,
wherein the contact pin has an elastic portion between the one and another end portions of the contact pin so as to be flexed in one direction and, before mounting of the socket body to the printed circuit board, the one end portion of the contact pin is positioned so as to project outward through one through hole formed to the socket body and bent and inclined in a same direction as the flexed direction with respect to a perpendicular direction.
In another aspect, there is provided a socket for an electrical part having a socket body to which a number of contact pins are arranged, in which the each of the contact pins has one end portion which electrically contacts a terminal of an electrical part and another one end portion which electrically contacts a printed circuit board,
wherein the contact pin has an elastic portion between the one and another end portions of the contact pin so as to be flexed in one direction and, before accommodation of the electrical part in the socket body, the another one end portion of the contact pin is positioned so as to project outward through another one through hole formed to the socket body and bent and inclined in a same direction as the flexed direction with respect to a perpendicular direction.
In a further aspect, there is also provided a socket for an electrical part having a socket body to which a number of contact pins are arranged, in which the each of the contact pins has one end portion which electrically contacts a terminal of an electrical part and another one end portion which electrically contacts a printed circuit board,
wherein the contact pin has an elastic portion between the one and another end portions of the contact pin so as to be flexed in one direction and, the one and another end portions of the contact pin are positioned so as to project outward through one and another through holes, respectively, formed to the socket body and bent and inclined in a same direction as the flexed direction with respect to a perpendicular direction.
In a further preferred aspect, there is provided a socket for an electrical part comprising:
a socket body having a base portion and an upper plate disposed above the base portion; the socket body being provided with a number of contact pins which contact terminals of the electrical part for electrical connection between the terminals and a printed circuit board;
an open/close member mounted to the base portion of the socket body to be pivotal with respect thereto; and
a pressing member mounted to the open/close member for pressing the electrical part,
each of the contact pins having one end portion which electrically contacts the terminal of the electrical part, another one end portion which electrically contacts the printed circuit board and an elastic portion between the one and another end portions of the contact pin so as to be flexed in one direction, and the one and another end portions of the contact pin being positioned, so as to project outward through one through hole formed to the upper plate and through another one through hole formed to the base portion, respectively, and bent and inclined in a same direction as the flexed direction with respect to a perpendicular direction.
In the above respective aspect, the elastic portion may have an arcuate shape, angled bent shape or substantially S-shape flexed in a direction with respect to the perpendicular direction.
According to the structures of the present invention mentioned above, the contact pin is composed of the one (upper) end portion, the other (lower) end portion and the intermediate elastic portion which is flexed in one direction with respect to the perpendicular direction. The upper end portion of the contact pin projects upward through the upper through hole formed to the socket body (upper plate) to be bent and inclined in the same direction as the flexed direction of the elastic portion.
Therefore, when the upper end portion of the contact pin is pressed downward, the elastic portion is flexed and deformed downward, and at its position, the upper end portion is directed substantially perpendicularly, so that the interference of the upper end portion with the peripheral edge portion of the upper through hole can be prevented and smooth operation can be achieved to thereby ensure the electrical contact between the terminal of the electrical part and the contact pin.
On the other hand, in another aspect, the lower end portion of the contact pin projects downward through the lower through hole formed to the socket body (base portion) to be bent and inclined in the same direction as the flexed direction of the elastic portion.
Therefore, when the lower end portion of the contact pin is pressed upward, the elastic portion is flexed and deformed upward, and at its position, the lower end portion is directed substantially perpendicularly, so that the interference of the lower end portion with the peripheral edge portion of the lower through hole can be prevented and smooth operation can be achieved to thereby ensure the electrical contact between the terminal of the electrical part and the contact pin.
In the other aspects of the embodiment, the upper and lower end portions of the contact pin are both projects through the upper and lower through holes of the socket body, so that the interference of these upper and lower end portions of the contact pin with the peripheral edge portions of the upper and lower holes can be effectively prevented, thus performing the smooth operation and ensuring the electrical contact.
The nature and further characteristic features of the present invention will be made more clear from the following descriptions made with reference to the accompanying drawings.